Cooking oven with improved heat distribution manifold system

ABSTRACT

A cooking oven manifold system includes a conveyor extending through a housing and a plurality of air manifolds positioned above and below the conveyor, each air manifold having a pair of sidewalls extending between a back wall and an inlet. A pair of outlet nozzles extend along a length of each air manifold. An angled surface between each pair of outlet nozzles extends along a length of the air manifold. Each air manifold is additionally spaced apart from each adjacent air manifold to create an air gap between sidewalls of adjacent air manifolds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a manifold system for directing air flowacross a conveyor within a cooking oven for cooking of food products.

2. Description of Prior Art

Linear cooking ovens for cooking food typically include a conveyor orconveyor belt for conveying food to be cooked from an inlet to an outletand through a cooking chamber. A heat source, air mover and heatexchanger are typically provided within the cooking chamber for cookingthe food provided on the conveyor.

Existing linear cooking ovens are typically difficult to maintain andclean because of condensate, oil droplets and other fluids and particlesthat may accumulate in and around the heat exchanger. As a result,costly line interruptions and/or disassembly are necessary to maintainthe rigid hygienic standards required for such linear cooking ovens.Cleaning and maintenance on existing linear cooking ovens often involvesheat exchangers that fold or rotate into a cleaning position therebyrequiring flexible hoses, connections and other components to permitease of movement of the heat exchanger.

In addition, a uniform and consistent cooking environment is difficultto maintain in existing cooking ovens because of a lack of proper airflow, recirculation, heat exchange and other factors.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a cooking oventhat provides uniform and controllable cooking conditions within acooking chamber and/or along a conveyor.

It is another object of this invention to provide a cooking oven havingcomponents that are modular.

It is another object of this invention to provide a cooking oven whichis easily cleaned.

It is still another object of this invention to provide a cooking oventhat separates the heat exchanger from the conveyor so that food on theconveyor is not contaminated by discharge and/or accumulations on theheat exchanger.

It is yet another object of this invention to provide a cooking oventhat utilizes return air from the conveyor into continuous cycles of airflow through an air distribution system.

A linear cooking oven according to one preferred embodiment of thisinvention is preferably a modular oven which may have any desired numberof interchangeable modules. The cooking oven preferably includes ahousing having an inlet and an outlet and an enclosed chamber. Aconveyor extends between the inlet and the outlet and through thechamber.

An air distribution system is positioned in fluid communication with thechamber and may include one or more blowers or other devices forcirculating conditioned air throughout the chamber. The air distributionsystem is preferably positioned above the conveyor and adjacent a curvedheat exchanger. The curved heat exchanger directs air from the airdistribution system through the chamber and across the conveyor. Thecurved heat exchanger preferably includes an air inlet and an air outletpositioned in a non-linear relationship relative to the air inlet withat least a partially curved surface between air the inlet and the airoutlet.

As a result of the described configuration of the cooking oven, thecurved heat exchanger preferably directs air flow from a top portion ofchamber to a lower portion of chamber and across the conveyor. One ormore air manifolds are preferably connected with respect to the cookingoven so as to more precisely direct air flow from the air distributionsystem to the conveyor. Preferably, a plurality of air manifolds arepositioned along the conveyor, preferably both above and below theconveyor.

Each air manifold includes a pair of sidewalls extending between a backwall and an inlet of the respective air manifold. A pair of outletnozzles preferably extend along a length of each air manifold betweenthe back wall and the inlet. In addition, in an alternate embodiment ofthis invention, an angled surface within each outlet nozzle preferablyextends along a length of the air manifold. In arrangements of multipleair manifolds, each air manifold is spaced apart from each adjacent airmanifold to create an air gap between sidewalls of adjacent airmanifolds. Air directed through the air manifolds impinges on the fooditems on the conveyor where heat is drawn out into the food items. Thecooled return air is then delivered through the air distribution system.Return air from the conveyor is delivered through the plurality of airgaps between the air manifolds.

According to one preferred embodiment of this invention, the cookingoven further includes a damper system comprising a plurality of louversconnected with respect to at least one upper manifold and at least onelower manifold. The plurality of louvers is adjustable to control theair flow between the upper manifold and the lower manifold. A manual orelectronic adjustment arm may be affixed with respect to the pluralityof louvers to route air flow between the upper manifold and the lowermanifold. Preferably, when at least one louver in the upper manifold isopened, at least one other corresponding louver is closed in the lowermanifold.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and objects of this inventionwill be better understood from the following detailed description takenin conjunction with the drawings wherein:

FIG. 1 is a side view of a cooking oven according to one preferredembodiment of this invention;

FIG. 2 is a top view of the cooking oven shown in FIG. 1;

FIG. 3 is a front view of the cooking oven shown in FIG. 1;

FIG. 4 is top view of a heat exchanger according to one preferredembodiment of this invention;

FIG. 5 is a front view of the heat exchanger shown in FIG. 4;

FIG. 6 is a side view of the heat exchanger shown in FIG. 4;

FIG. 7 is a cross-sectional view of a portion of the heat exchangershown in FIG. 5 according to one preferred embodiment of this invention;

FIG. 8 is a top view of a cooking oven according to one preferredembodiment of this invention;

FIG. 9 is a side view of the cooking oven shown in FIG. 8;

FIG. 10 is a front view of the cooking oven shown in FIG. 8;

FIG. 11 is a side view of a manifold according to one preferredembodiment of this invention;

FIG. 12 is a bottom view of the manifold shown in FIG. 11;

FIG. 13 is a top view of the manifold shown in FIG. 11;

FIG. 14 is a front view of the manifold shown in FIG. 11;

FIG. 15 is a side perspective view of the manifold shown in FIG. 11;

FIG. 16 is a front perspective view of a portion of a cooking ovenincluding a plurality of manifolds according to one preferred embodimentof this invention;

FIG. 17 is a side view of an upper manifold and a lower manifoldaccording to one preferred embodiment of this invention;

FIG. 18 is a side perspective view of a portion of a cooking ovenincluding a plurality of louvers according to one preferred embodimentof this invention; and

FIG. 19 is a front schematic view of the cooking process according toone preferred embodiment of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1-3 show a linear cooking oven according to one preferredembodiment of this invention. Cooking oven 10 is preferably a modularoven which may have any desired number of modules 12 joined together inan end-to-end relationship. Cooking oven 10 having three modules 12 isshown for purposes of illustration.

As shown, cooking oven 10 includes housing 15 having inlet 17 and outlet19. Housing 15 encloses chamber 30, namely a cooking chamber. Conveyor40, preferably a conveyor belt or similar device known to those havingordinary skill in the art, extends between inlet 17 and outlet 19 andthrough chamber 30. Conveyor 40 is preferably a pervious belt thuspermitting air and liquid to flow through.

According to a preferred embodiment of this invention, conveyor 40operates continuously whenever cooking oven 10 is in operation. Thus,cooking oven 10 may be referred to as a continuous oven. Uncooked foodis loaded onto conveyor 40 continuously at inlet 17 and transportedthrough one or more modules 12 in succession, and emerges cooked, at theoutlet end of the oven. As the food passes through cooking oven 10, theindividual modules 12 may operate either under the same or differentcooking conditions. Since each individual module 12 contains distinctcomponents as described herein, each individual module 12 may be tuneddifferently to create different cooking environments and conditions. Forexample, one module 12 may be operated with steam only and a subsequentmodule 12 may be operated with a mixture of hot air or gas and steam ata higher temperature than the first module 12. As such, according to onealternative embodiment of this invention, the first module 12 may beoperated as a preheat module and a last module 12 may be operated as acool-down module, although for greater efficiency it is preferable topreheat the food product before entering cooking oven 10 and cool downthe food product after exiting cooking oven 10.

Additionally, one or more modules 12 may operate with a damper systemdirecting heated air to the upper manifold (as described below), one ormore modules 12 may operate with the damper system directing heated airto the lower manifold (described below), and one or more modules 12 mayoperate with heated air directed to both the upper manifold and lowermanifold, to provide overall optimum cooking of the food items. However,according to a preferred embodiment of this invention, each module 12will direct heated air to the upper manifold and lower manifold equally.According to an alternative three module 12 embodiment, a first and athird module 12 will direct heated air to the upper manifold and asecond module 12 will direct air to the lower manifold.

As shown in FIGS. 1-3, air distribution system 50 is positioned in fluidcommunication with chamber 30. Air distribution system 50 preferablyincludes one or more fans, blowers 55 or other devices for circulatingconditioned air to air manifolds which upon impinging on food itemsreturns through air distribution system 50. Air distribution system 50may include a combination of forced draft air flow and induced air flowto generate proper and uniform conditions throughout cooking oven 10. Asshown in FIGS. 9 and 10, air distribution system 50 is preferablypositioned above conveyor 40.

As used in this specification and claims, air flow is defined asconditioned air, vapor, gas and/or fluid used to circulate throughcooking oven 10. According to one preferred embodiment of thisinvention, air flow comprises steam.

Curved heat exchanger 60, for instance as shown in FIGS. 4-7, ispreferably positioned in fluid communication with chamber 30, as shownin FIGS. 8-10. Curved heat exchanger 60 preferably directs air from theair distribution system 50 through chamber 30 and across conveyor 40.

According to one preferred embodiment of this invention, and as shown inFIGS. 4-7, curved heat exchanger 60 includes air inlet 62 and air outlet66. Air inlet 62 is preferably positioned in at least approximately a90° relationship relative to air outlet 66 with at least a partiallycurved surface between air inlet 62 and air outlet 66.

According to one preferred embodiment of this invention, a plurality ofcurved plates 65 are positioned between air inlet 62 and air outlet 66.The plurality of curved plates 65 preferably extend generally parallelwith respect to each other for at least a portion, if not all, of the alength of curved heat exchanger 60.

As shown in cross-section in FIG. 7, curved plates 65 may include ahollow portion or channel 68 for containing and transporting a thermalfluid, such as oil. One channel 68 may adjoin each curved plate 65 asshown. The fluid passing through channels 68 serves to elevate the heatexchanger plates 65 to a desired temperature or temperature range. Awide variety of heating fluids may be passed through channels 68,including various types of heating oils, steam or super heated steam.Alternatively, plates 65 may be heated by another means such aselectrical induction.

According to one preferred embodiment of this invention, curved heatexchanger 60 may be cleaned by raising and/or lowering a hood and/orhousing 15 to access curved heat exchanger 60. Alternatively, and incontrary fashion to the preferred embodiment of this invention, cookingoven 10 may include an apparatus for raising and/or lowering curved heatexchanger 60 to provide easy access for cleaning, servicing, etc.

As a result of the described configuration of cooking oven 10, curvedheat exchanger 60 preferably directs air flow from a top portion ofchamber 30 to a lower portion of chamber 30 and across conveyor 40. Assuch, curved heat exchanger 60 extends vertically from air inlet 62 andhorizontally from air outlet 66. Curved heat exchanger 60 may therebydirect air flow from air inlet 62 facing an upper portion of chamber 30and through air outlet 66 facing conveyor 40 so that air inlet 62 ispositioned at approximately a right angle relative to air outlet 66.

According to one preferred embodiment of this invention, curved heatexchanger 60 is positioned outside of a vertical boundary defined byedges of conveyor 40. As a result of such a configuration, conveyor 40,and food thereon, will not be contaminated by dripping oil, water andother contaminants.

A primary advantage of curved heat exchanger 60 is its ability to directthe flow of heated air to the air manifolds in a horizontal or nearlyhorizontal direction while simultaneously relying on gravity and airflow to facilitate cleaning between heat exchanger plates 65. Becauseportions of curved heat exchanger 60 are vertical or nearly vertical,oil droplets and other contaminants which are collected between plates65 tend to flow forward, and are discharged from the downstream end ofcurved heat exchanger 60 instead of accumulating between plates 65. Theuseful operating time, which is the time between shutdowns of cookingoven 10 for cleaning and maintenance of the heat exchanger, is greatlyincreased when curved heat exchanger 60 of the invention is used, asopposed to a conventional tube and fin or other heat exchangers. Also,the curved configuration of curved plates 65 allows for a more compactfit of curved heat exchanger 60 within cooking oven 10.

Curved heat exchanger 60 may be curved along the entire length of plates65 as shown in FIG. 6. Alternatively, curved heat exchanger 60 need notbe curved along the entire length of plates 65, so long as there is atleast one curved portion or corner. For instance, curved plates 65 mayhave a straight portion and a curved portion, a straight portion and twocurved portions, two straight portions and a curved portion, and so on.

Curved heat exchanger 60 may include plates 65 which are curved at anangle of 90 degrees as shown in FIG. 6. Alternatively, depending uponthe application, the total angle of curvature may range between about20-180 degrees, suitably between about 30-150 degrees, likely betweenabout 45-135 degrees, desirably between about 60-120 degrees. The totalangle of curvature may be defined as the angular difference betweenplates 65 at air inlet 62 and air outlet 66 of curved heat exchanger 60.This way, if curved heat exchanger 60 has more than one curved portion,the curvatures of the multiple portions are added together to arrive atthe total angle of curvature for curved heat exchanger 60. The radius orradii of curvature may also vary, depending on the size and shape ofcooking oven 60.

Depending upon the flow pattern of air within cooking oven 10, curvedheat exchanger 60 may be positioned in various parts of cooking oven foroptimum performance. To facilitate self-cleaning of curved heatexchanger 60, with the aid of gravity, air inlet 62 should be at ahigher elevation than air outlet 66, as shown in FIG. 6, for instance.

Generally speaking, chamber 30 preferably includes a platform in linewith the air distribution system, an air mover positioned over theplatform and curved heat exchanger 60 positioned adjacent to theplatform and redirecting air from the air mover across the platform.According to such an embodiment, the platform may comprise conveyor 40,cooking surface, or any other surface requiring redirected heat from anair mover and/or heat source to another location with chamber 30.

More specifically, according to one preferred embodiment of thisinvention, curved heat exchanger 60 is positioned adjacent conveyor 40and directs air from above conveyor 40 through chamber 30 and preferablythrough a damper system and/or a plurality of manifolds, as described inmore detail below, whereupon such air is impinged on the food items andthe cooled return air is then delivered through the air distributionsystem.

Manifold System

FIGS. 11-15 show various views of air manifold 80 according to onepreferred embodiment of this invention. Air manifold 80 is preferablyconnected with respect to cooking oven 10 so as to direct air flow fromair distribution system 50 to conveyor 40.

According to one preferred embodiment of this invention, a plurality ofair manifolds 80 are positioned along conveyor 40, preferably above andbelow conveyor 40. One or more air manifolds 80 are preferablypositioned within each module 12 of cooking oven 10 thereby permittingfree and compatible exchange/addition/subtraction of modules 12 withincooking oven 10.

Air manifold 80 includes a pair of sidewalls 85 extending between backwall 83 and inlet 81. A pair of outlet nozzles 90 preferably extendalong a length of each air manifold 80 between back wall 83 and inlet81.

In addition, according to an additional embodiment of this invention, anangled surface 95 constitutes a floor of air manifold 80 between theoutlet nozzles 90, and extends along a length of air manifold 80.According to one preferred embodiment of this invention, the angledsurface 95 extends between the outlet nozzles 90 from inlet 81 to alower half of back wall 83 of air manifold 80. Angled surface 95 helpsto ensure an even or uniform air pressure along the length of airmanifold 80, resulting in more uniform velocity of air ejected along thelength of nozzles 90. If angled surface 95 of air manifold 80 werehorizontal instead of angular, the air pressure and velocity would behigher at locations closer to inlet 81, and lower closer to back wall83. Angled surface 95 helps overcome the variable air pressure thatwould otherwise exist based on the distance from inlet 81.

Angled surface 95 extending across outlet nozzle 90 preferably equalizesa pressure of the conditioned air across angled surface 95 therebycreating a uniform air flow out of outlet nozzle 90 and across a widthof conveyor 40. Uniform air flow is important for uniform cookingconditions within cooking oven 10. Depending upon the application,angled surface 95 may have an angle of about 5 to 50 degrees fromhorizontal, suitably about 10 to 40 degrees, desirably about 15 to 30degrees.

As shown in the figures, according to one preferred embodiment of thisinvention wherein air manifolds 80 are positioned over conveyor 40,inlet 81 and the pair of outlet nozzles 90 of each air manifold 80extend in the same direction. Therefore, air flow is directed upwardlyinto inlet 81 from air distribution system 50 and then across airmanifold 80 and back downward through outlet nozzles 90 across thelength of air manifold 80.

Each air manifold 80 includes a rectangular space 91 resembling athree-sided box, open at the bottom (toward conveyor 40), betweennozzles 90. Some of the heated air which leaves nozzles 90 contacts thefood items and/or conveyor 40, then deflects upward into the space 91,where it is carried back down by the venturi effect of the heated airleaving nozzles 90. This recirculation of heated air helps to mix thecooking air and facilitates more uniform cooking.

In arrangements of multiple air manifolds 80, such as shown in FIG. 16,each air manifold 80 is spaced apart from each adjacent air manifold 80to create an air gap 87 between sidewalls 85 of adjacent air manifolds80. Return air from conveyor 40 is preferably delivered through aplurality of air gaps 87 between sidewalls 85 of adjacent air manifolds80 in cooking oven 10.

According to one preferred embodiment of this invention, each outletnozzle 90 comprises a narrower opening than either a width of air gap 87or a width of air manifold 80. A relatively narrow opening of eachoutlet nozzle 90 results in concentrating heating and/or cooling of thefood product positioned on conveyor 40.

In one particular embodiment of this invention, air manifolds 80 arespaced approximately 6″ apart from each other. In such embodiment, anair manifolds 80 above conveyor 40 include outlet nozzles 90 spacedapproximately 10″ apart from each other within each air manifold 80. Inyet another embodiment, air manifolds 80 are spaced approximately 8″apart from each other and outlet nozzles 90 are spaced approximately 8″apart from each other. Air manifolds 80 below conveyor 40 preferablyinclude outlet nozzles 90 spaced approximately 2.5″ apart from eachother within each air manifold 80.

Damper System

According to one preferred embodiment of this invention shown in FIGS.17 and 18, cooking oven 10 further includes a damper system comprising aplurality of louvers 70 connected with respect to upper manifold 101 andlower manifold 105, the plurality of louvers 70 adjustable to controlthe air flow between the upper manifold 101 and lower manifold 105.

As shown in FIG. 18, adjustment arm 75 may be additionally connectedwith respect to the plurality of louvers 70. Adjustment arm 75preferably opens at least one louver of the plurality of louvers 70 andcorrespondingly closes at least one other louver of the plurality oflouvers 70 to control air flow between upper manifold 101 and lowermanifold 105. Adjustment arm 75 may be manually controlled orelectronically controlled.

As best shown in FIG. 17, inlet manifold 73 is preferably connected withrespect to the plurality of louvers 70 to route air flow includingreturn air from conveyor 40 and primary air from heat exchanger 60.Because of the described arrangement of recirculated air, this inventionnecessarily requires primary air from heat exchanger 60 and return airfrom conveyor 40. The plurality of louvers 70 preferably extend along atleast a portion of a length of the conveyor 40.

As shown in FIG. 18, a first plurality of louvers 70 may be arranged inan array across upper manifold 101 and a second plurality of louvers 70may be arranged in an array across lower manifold 105. The firstplurality of louvers 70 and the second plurality of louvers 70 may bearranged in subgroups across upper manifold 101 and lower manifold 105,respectively. For instance, as shown in FIG. 18, subgroups of threelouvers 70 may be positioned in an array across upper manifold 101and/or lower manifold 105.

As a result of the described arrangement of louvers 70, air flow isdirected and controlled through and between the plurality of louvers 70connected with respect to upper manifold 101 and the lower manifold 105.Preferably, when at least one louver 70 in upper manifold 101 is opened,at least one other corresponding louver 70 is closed in lower manifold105 thereby controlling air flow between the upper manifold 101 and thelower manifold 105. More specifically, as an array of louvers 70 isopened in upper manifold 101, a corresponding array of louvers 70 isclosed in lower manifold 105.

One advantage of this arrangement is that the total heated air flow canbe maintained at a constant rate in a given module 12. The damper systemdirectes the heated air to upper manifold 101, lower manifold 105, or adesired combination of both, without changing the total amount of heatedair supplied for cooking. Thus, the amount of heated air can be fixedand controlled at a predetermined rate as desired to give the optimumlevel of overall cooking. The damper system can be used to direct air toupper and lower manifolds 101, 105 as desired to ensure that the cookingis substantially uniform and even.

While in the foregoing specification this invention has been describedin relation to certain preferred embodiments thereof, and many detailshave been set forth for purpose of illustration, it will be apparent tothose skilled in the art that this invention is susceptible toadditional embodiments and that certain of the details described hereincan be varied considerably without departing from the basic principlesof the invention.

We claim:
 1. A cooking oven manifold system comprising: a conveyorextending through a housing; a plurality of air manifolds positionedabove and below the conveyor, each air manifold having a pair ofsidewalls extending along a length of each air manifold between a backwall and an inlet; a pair of outlet nozzles, each outlet nozzle of thepair of outlet nozzles extending toward the conveyor and along thelength of each air manifold; and each air manifold spaced apart fromeach adjacent air manifold to create an air gap between sidewalls ofadjacent air manifolds.
 2. The cooking oven manifold system of claim 1further comprising: an angled surface between each pair of outletnozzles extending along a length of the air manifold.
 3. The cookingoven manifold system of claim 2 wherein the angled surface extendsbetween each pair of outlet nozzles from the inlet to a lower half of aback wall of the air manifold.
 4. The cooking oven manifold system ofclaim 1 wherein air flow into the inlet and out of the pair of outletnozzles of each air manifold extends in a generally common plane and ingenerally opposite directions.
 5. The cooking oven manifold system ofclaim 1 wherein each outlet nozzle comprises a narrower opening thaneither a width of the air gap or a width of the air manifold.
 6. Thecooking oven manifold system of claim 1 wherein each air manifoldpositioned above the conveyor is configured differently from each airmanifold positioned below the conveyor.
 7. The cooking oven manifoldsystem of claim 6 wherein each air manifold positioned above theconveyor includes a wider distance between outlet nozzles than each airmanifold positioned below the conveyor.
 8. The cooking oven manifoldsystem of claim 5 wherein each air manifold positioned above theconveyor includes outlet nozzles having a different size than outletnozzles in each air manifold positioned below the conveyor.
 9. A methodof cooking using a manifold system extending around a conveyor, themethod comprising the steps of: arranging a plurality of air manifoldsabove the conveyor, each air manifold having a pair of sidewallsextending along a length between a back wall and an inlet; forcingconditioned air through a pair of outlet nozzles toward the conveyor,each outlet nozzle of the pair of outlet nozzles extending along thelength of each air manifold; heating food product on the conveyor withthe conditioned air; and delivering return air from the conveyor througha plurality of air gaps between sidewalls of adjacent air manifolds ofthe plurality of air manifolds.
 10. The method of claim 9 furthercomprising the step of: forcing air across an angled surface along thelength of each air manifold; and equalizing a pressure of theconditioned air across the angled surface extending through each outletnozzle from the inlet to a lower half of a back wall of the manifold.11. The method of claim 9 further comprising the step of: arranging asecond plurality of air manifolds below the conveyor.
 12. The method ofclaim 9 wherein air flow into the inlet and out of the pair of outletnozzles of each air manifold extend in a generally common plane and inopposite directions.
 13. The method of claim 9 wherein each outletnozzle comprises a narrower opening than either a width of the air gapor a width of the air manifold.
 14. A cooking oven manifold systemcomprising: a conveyor extending through a housing; a plurality of airmanifolds positioned above the conveyor, each air manifold having a pairof sidewalls extending along a length between a back wall and an inlet;a pair of outlet nozzles, each outlet nozzle of the pair of outletnozzles extending along the length of each air manifold, wherein airflow into the inlet and out of the pair of outlet nozzles of each airmanifold generally flows in a common plane perpendicular with theconveyor and in opposite directions; each air manifold spaced apart fromeach adjacent air manifold to create an air gap between sidewalls ofadjacent air manifolds; and a plurality of louvers controlling the airflow through the plurality of air manifolds.
 15. The cooking ovenmanifold system of claim 14 further comprising: an angled surfaceextending along a length of each adjacent air manifold, wherein theangled surface extends through each outlet nozzle from the inlet to alower half of a back wall of the air manifold.
 16. The cooking ovenmanifold system of claim 14 wherein each outlet nozzle comprises anarrower opening than either a width of the air gap or a width of theair manifold.
 17. The cooking oven manifold system of claim 14 furthercomprising a plurality of air manifolds positioned below the conveyor.18. The cooking oven manifold system of claim 17 wherein each airmanifold positioned above the conveyor is configured differently fromeach air manifold positioned below the conveyor.
 19. The cooking ovenmanifold system of claim 17 wherein the plurality of louvers control airflow between the plurality of air manifolds above the conveyor and theplurality of air manifolds below the conveyor.
 20. The cooking ovenmanifold system of claim 17 wherein each air manifold positioned abovethe conveyor includes different outlet nozzles than each air manifoldpositioned below the conveyor.